In a processing machine, the stability of main shaft assembly is one of the key factors determining the processing precision and the completion degree. Generally, the shape of the main shaft in the main shaft assembly of the processing machine is a circular column or a rectangular column.
Taking a circular column shaped main shaft as an example, the ideal status is to keep the roundness of the cylindrical surface of the circular column shaped main shaft. However, to achieve such high processing precision, the manufacturing cost of the main shaft will be increased significantly. Taking a rectangular column shaped main shaft as an example, and comparing it with the circular column shaped main shaft, the rectangular column shaped main shaft has a poorer pressure dispersion performance, and therefore deformation is likely to occur on the column surface.
In addition, during the manufacturing process of the foregoing main shafts, it is unlikely to completely eliminate the tolerance. Furthermore, the amount of deformation generated when a force is applied to the circular or rectangular column shaped main shaft is large, so that the perpendicularity of the main shaft assembly is unsatisfactory, the centrality deviates, the precision of endpoint processing deviates, and even cutter vibration occurs, which results in an unsatisfactory completion degree of a processed object. Moreover, the foregoing situations also relatively shorten the service life of the main shaft and the cutting tool.
Therefore, how to reduce the amount of deformation when forces are applied to the main shaft, that is, how to improve the rigidity and bending resistance performance of the main shaft is a problem needs to be solved. Some manufacturers put forward the design of an octagonal column shaped main shaft to improve the bending resistance performance of the main shaft. Although the bending resistance performance of the octagonal column shaped main shaft is improved, but still not good enough to resist the bending.